The invention relates to a fuel injection system for an internal combustion engine which includes a measuring device for measuring air quantity supplied to the engine, a metering valve for metering fuel to be injected in proportion to the supplied air quantity and a control valve downstream of the metering valve for controlling the pressure difference at the metering valve, and thus the air/fuel ratio, as a function of selected engine operating parameters. The control valve is embodied as a differential pressure valve including a movable valve element having one side subjected to the fuel pressure downstream of the metering valve and an opposite side subjected to the pressure of a control pressure line. One end of the control pressure line is connected to a pressure source. The control pressure is relieved at an opposite end of the control pressure line by an electromagnetic valve which is actuated to vary the air/fuel ratio in accordance with the selected engine operating parameters.
However in known fuel injection systems of this type such as that described in U.S. Pat. No. 4,064,854, issued Dec. 27, 1977 to Fehrenbach et al; there is the disadvantage that in the event of acceleration, if the metering valves are suddenly opened, the fuel pressure in the chambers of the control valves downstream of the metering valves increases, because the pressure in the chambers of the control valves communicating with the control pressure line does not drop rapidly enough. The pressure increase at the metering valves causes too small a fuel quantity to be metered for that operational state of the engine.